检索结果-南通市图书馆

Thickness Effect on (La_(0.26)Bi_(0.74))_2Ti_4O_(11) Thin-Film Composition and Electrical Properties

在线全文

学校读者我要写书评

暂无评论

Chinese Physics Letters 2018年第2期35卷 66-70页

作者： hui-zhen Guo An-Quan Jiang State Key Laboratory of ASIC & System School of MicroelectronicsFudan University

Highly oriented（00l）（La_（0.26）Bi_（0.74））_2Ti_4O_（11 ）thin films are deposited on（100） SrTiO_（3 ）substrates using the pulsed laser deposition *** grains form a texture of bar-like arrays along Sr Ti O_3110directions for the film thickness above 350 nm,in contrast to spherical grains for the reduced film thickness below 220 nm.X-ray diffraction patterns show that the highly ordered bar-like grains are the ensemble of two lattice-matched monoclinic（La,Bi）_4Ti_3O_（12 ）and TiO_（2 ）components above a critical film ***,the phase decomposes into the random mixture of Bi_2Ti_2O_（7 ）and Bi_4Ti_3O_（4 ）spherical grains in thinner *** critical thickness can increase up to 440 nm as the films are deposited on LaNiO_3-buffered SrTiO_（3 ）*** electrical measurements show the dielectric enhancement of the multi-components,and comprehensive charge injection into interfacial traps between（La,Bi）_4Ti_3O_（12 ）and TiO_（2 ）components occurs under the application of a threshold voltage for the realization of high-charge storage.

关键词： Bi Ti Thin-Film Composition and Electrical Properties LNO La

Irrigation water salinity and N fertilization:Effects on ammonia oxidizer abundance, enzyme activity and cotton growth in a drip irrigated cotton field

在线全文

学校读者我要写书评

暂无评论

Journal of Integrative Agriculture 2016年第5期15卷 1121-1131页

作者： MIN Wei GUO hui-juan ZHANG Wen ZHOU Guang-wei ma Li-juan YE Jun HOU zhen-an Department of Resources and Environmental Science Shihezi University

Use of saline water in irrigated agriculture has become an important means for alleviating water scarcity in arid and semi-arid regions. The objective of this field experiment was to evaluate the effects of irrigation water salinity and N fertilization on soil physicochemical and biological properties related to nitrification and denitrification. A 3×2 factorial design was used with three levels of irrigation water salinity（0.35, 4.61 and 8.04 d S m-1） and two N rates（0 and 360 kg N ha^（-1））. The results indicated that irrigation water salinity and N fertilization had significant effects on many soil physicochemical properties including water content, salinity, p H, NH_4-N concentration, and NO_3-N concentration. The abundance（i.e., gene copy number） of ammonia-oxidizing archaea（AOA） was greater than that of ammonia-oxidizing bacteria（AOB） in all treatments. Irrigation water salinity had no significant effect on the abundance of AOA or AOB in unfertilized plots. However, saline irrigation water（i.e., the 4.61 and 8.04 d S m-1 treatments） reduced AOA abundance, AOB abundance and potential nitrification rate in N fertilized plots. Regardless of N application rate, saline irrigation water increased urease activity but reduced the activities of both nitrate reductase and nitrite reductase. Irrigation with saline irrigation water significantly reduced cotton biomass, N uptake and yield. Nitrogen application exacerbated the negative effect of saline water. These results suggest that brackish water and saline water irrigation could significantly reduce both the abundance of ammonia oxidizers and potential nitrification rates. The AOA may play a more important role than AOB in nitrification in desert soil.

关键词： saline water nitrogen fertilizer ammonia-oxidizing microorganisms enzyme activity cotton yield

Recent progress in design of conductive polymers to improve the thermoelectric performance

在线全文

学校读者我要写书评

暂无评论

Chinese Physics B 2022年第2期31卷 22-32页

作者： zhen Xu hui Li Lidong Chen State Key Laboratory of High Performance Ceramics and Superfine Microstructures Shanghai Institute of CeramicsChinese Academy of SciencesShanghai 200050China Center of materials Science and Optoelectronics Engineering University of Chinese Academy of SciencesBeijing 100049China

Organic semiconductors,especially polymer semiconductors,have attracted extensive attention as organic thermoelectric materials due to their capabilities for flexibility,low-cost fabrication,solution processability and low thermal ***,it is challenging to obtain high-performance organic thermoelectric materials because of the low intrinsic carrier concentration of organic *** main method to control the carrier concentration of polymers is the chemical doping process by charge transfer between polymer and ***,the deep understanding of doping mechanisms from the point view of chemical structure has been highly desired to overcome the bottlenecks in polymeric *** this contribution,we will briefly review the recently emerging progress for discovering the structure–property relationship of organic thermoelectric materials with high *** include some achievements about doping strategies to effectively modulate the carrier concentration,the design rules of building blocks and side chains to enhance charge transport and improve the doping ***,we will give our viewpoints on the challenges and opportunities in the field of polymer thermoelectric materials.

关键词： conductive polymer organic thermoelectric material chemical doping side chain engineering

Crystalline mesoporous transition metal oxides： hard-templating synthesis and application in environmental catalysis

在线全文

学校读者我要写书评

暂无评论

Frontiers of Environmental Science & Engineering 2013年第3期7卷 341-355页

作者： zhen ma Bei ZHOU Yu REN Shanghai Key Laboratory of Atmospheric Particle Pollution and Prevention (LAp3) Department of Environmental Science and Engineering Fudan University Shanghai 200433 China Energy Storage Center National Institute of Clean-and-Low-Carbon Energy Shenhua Group Future Science and Technology City Beijing 102209 China

Mesoporous silicas such as MCM-41 and SBA-15 possess high surface areas, ordered nanopores, and excellent thermal stability, and have been often used as catalyst supports. Although mesoporous metal oxides have lower surface areas compared to mesoporous silicas, they generally have more diversified functionalities. Mesopor- ous metal oxides can be synthesized via a soft-templating or hard-templating approach, and these materials have recently found some applications in environmental cata- lysis, such as CO oxidation, N20 decomposition, and elimination of organic pollutants. In this review, we summarize the synthesis of mesoporous transition metal oxides using mesoporous silicas as hard templates, high- light the application of these materials in environmental catalysis, and furnish some prospects for future develop- ment.

关键词： Keywords mesoporous materials silica metal oxide,hard-templating environmental catalysis

Dual ligands relay-promoted transformation of unstrained ketones to polyfluoroarenes and nitriles

在线全文

学校读者我要写书评

暂无评论

Science China Chemistry 2023年第7期66卷 2037-2045页

作者： zhen-Yu Wang huiying Xu Xu Zhang Xing Wang hui Xu hui Gao hui-Xiong Dai School of Chinese materia Medica Nanjing University of Chinese MedicineNanjing 210023China CAS Key Laboratory of Receptor Research State Key Laboratory of Drug ResearchShanghai Institute of Materia MedicaChinese Academy of SciencesShanghai 201203China School of Pharmaceutical Sciences Guangzhou Medical UniversityGuangzhou 511436China University of Chinese Academy of Sciences Beijing 100049China

C-C bond activation has emerged as a powerful tool for the construction of complex ***,we report a dual ligands relay-promoted transformation of unstrained aryl,alkenyl and alkynyl ketones to the corresponding polyfluoroarenes and nitriles via C-C(=O)bond cleavage and subsequent decarboxylative arylation *** polyfluoroarene and nitrile products are obtained in one pot under cyanide-free *** protocol features high atom economy,broad functional group tolerance and excellent heterocyclic *** late-stage functionalization of the drug and natural product demonstrated the synthetic utility of our ***,the decisive role of the dual ligands was clarified and the mechanistic rationale including theβ-C elimination as the rate-limiting step was supported by detailed density functional theory(DFT)studies.

关键词： C-C bond activation dual ligands relay unstrained ketones modification of drugs and natural products DFT study

同方期刊数据库

Synthesis, and Investigation of the Reactive Oxygen Species of a Novel Cyclicpeptide-2,6-dimethoxyhydroquinone-3- mercaptoacetic Acid Conjugate

在线全文

学校读者我要写书评

暂无评论

Chinese Chemical Letters 2001年第12期12卷 1075-1078页

作者： Yu Fei SONG hui Min zhen Institute of Molecular Science Shanxi University Taiyuan Teacher's College

In this paper, we report the synthesis of a potential anti-cancer agent: Cyclo[Val-Lys(DMQ-ma)-Gaba]. The cytotoxic agent conjugated to the N-terminal and the xi -amino group of lysine of the tripeptide is 2,6-dimethoxyhydroquinone-3-mercaptoacetic acid (DMQ-ma). By employing the rhodamine B degradation method and ESR spectra, we testify the reactive oxygen species - hydroxyl radicals produced by the drug.

关键词： 2,6-dimethoxyhydroquinone-3-mercaptoacetic acid cyclicpeptide

Space-surface bistatic synthetic aperture radar with navigation satellite transmissions: a review

在线全文

学校读者我要写书评

暂无评论

Science China(Information Sciences) 2015年第6期58卷 5-24页

作者： ANTONIOU Michail CHERNIAKOV Mikhail ma hui Electronic Electrical and Systems Engineering Department University of Birmingham School of Electronic and Information Engineering Beihang University

This paper reviews the theory and practice of Space-Surface Bistatic Synthetic Aperture Radar(SS-BSAR) using navigation satellites as transmitters. In recent years, this innovative technology has reached a maturity stage which allows it to be considered for a wide range of applications. The paper covers the fundamental aspects of this technology as a radar system, such as the resolution, power budget and Point Spread Function(PSF) analysis, as well as its signal processing aspects and the state of the art in terms of advanced SAR techniques that it enables. Finally, the theoretical aspects of the paper may be directly transferred to the more generic SS-BSAR concept.

关键词： bistatic synthetic aperture radar GNSS-based SAR space-surface bistatic SAR coherent change detection multi-perspective imaging

A Middle Triassic stem-neopterygian fish from China sheds new light on the peltopleuriform phylogeny and internal fertilization

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Science Bulletin 2016年第22期61卷 1766-1774页

作者： Guang-hui Xu Xin-Ying ma Key Laboratory of Vertebrate Evolution and Human Origins of Chinese Academy of Sciences Institute of Vertebrate Paleontology and Paleoanthropology Chinese Academy of Sciences

Internal fertilization and viviparity are easily observed and well studied in living neopterygian fishes(14teleostean families), but they are difficult to identify in extinct taxa due to the limitation of the fossil record. The Peltopleuriformes from the Middle to Late Triassic of Europe and South China are a stem group of Neopterygii that may have first evolved internal fertilization and viviparity in this clade because they show a highly modified anal fin in presumed males resembling the intromittent organ in living viviparous teleosts. Until recently, Peltopleurus lissocephalus and P. rugosus from the Ladinian/Anisian boundary(*242 ma) of Monte San Giorgio area in Switzerland and Italy represent the oldest record of Peltopleuriformes, and the phylogenetic interrelationships of this group remain controversial. Here, we report the discovery of a new peltopleuriform, Peltopleurus nitidus sp. nov., based on eleven well-preserved specimens from the early Middle Triassic(Pelsonian, Anisian, *244 ma)of Luoping, eastern Yunnan, China. The discovery documents the oldest convincing peltopleuriform, extending the geological range of this clade by proximately two million years. Results of the phylogenetic analysis recover *** at the base of Peltopleuridae, and provide robust support for the sister-group relationships of Peltopleuridae with Thoracopteridae within the Peltopleuriformes. The male anal fin of P. nitidus shows a primitive condition unknown in other peltopleuriforms. Comparative studies of the male anal fin in P. nitidus and other peltopleuriforms shed new light on the internal fertilization in this group.

关键词： Sexual dimorphism Viviparity Peltopleuridae Thoracopteridae Triassic

Passive GNSS-based SAR imaging and opportunities using Galileo E5 signals

在线全文

学校读者我要写书评

暂无评论

Science China(Information Sciences) 2015年第6期58卷 84-94页

作者： ma hui ANTONIOU Michail CHERNIAKOV Mikhail School of Electronic and Information Engineering Beihang University Electronic Electrical and Systems Engineering Department University of Birmingham

This paper investigates the feasibility of Galileo navigation satellites as transmitters of opportunity in passive bistatic synthetic aperture radar(SAR) systems from the perspectives of signal processing and experiment program. Experimental images obtained using a single Galileo channel, E5 a or E5 b, are presented and analyzed. The paper also puts forward the channel combination scheme to jointly process E5 a and E5 b channels, which brings up high-resolution possibilities for passive SAR technique. By employing the entire E5 band for imaging, the range resolution may be potentially increased by up to 5 times. Preliminary experimental results for this concept are demonstrated.

关键词： bistatic synthetic aperture radar(BSAR) GNSS-based SAR Galileo E5 channel combination